title: The harmful effects of aqueous contrast agents on the gastrointestinal tract: a study of mechanism and means of counteraction.
abstract: The effect of mildly and strongly hypertonic solutions on intestinal tone and motility was tested with aqueous contrast solutions and with mannitol as a control in 15 dogs. These experiments were repeated in animals premedicated with atropine sulfate and/or methysergide maleate. Intestinal motility was recorded on serial x-ray films. Tone and motility were estimated by variations of intestinal caliber and rate of transit of contrast solution, respectively. The results obtained contradict the currently accepted mechanism of action of iodinated contrast media on the intestinal tract, which assumes that the effect is osmotic like that of a saline laxative. Solutions of different osmolarity produce hyperperistalsis of the same magnitude. This effect begins rapidly after the onset of gastric emptying and much sooner than a significant osmotic fluid shift occurs. Atropine sulfate and methysergide maleate (serotonin blocker), when given individually, are incapable of completely inhibiting hyperperistalsis induced by hypertonic solutions. However, when these agents are given in combination, motility is completely inhibited. The evidence supports a serotonin role in the hyperperistalsis induced by hypertonic solutions, partly by direct action of serotonin on the smooth muscle cells and partly by indirect action on the intramural cholinergic ganglion cells. This concept offers a possible means of eliminating one of the adverse effects of aqueous contrast media on the gastrointestinal tract.
mesh_terms: D000818:Animals; D001285:Atropine / Q000494:pharmacology; D003287:Contrast Media / Q000009:adverse effects*; D003973:Diatrizoate / Q000009:adverse effects; D003974:Diatrizoate Meglumine / Q000494:pharmacology; D004064:Digestive System / Q000000981:diagnostic imaging / Q000187:drug effects*; D004068:Digestive System Physiological Phenomena; D004285:Dogs; D005769:Gastrointestinal Motility / Q000187:drug effects; D006982:Hypertonic Solutions; D007483:Iothalamic Acid / Q000009:adverse effects; D008353:Mannitol / Q000494:pharmacology; D008784:Methysergide / Q000494:pharmacology; D009129:Muscle Tonus / Q000187:drug effects; D011859:Radiography
chemical_list: D003287:Contrast Media; D006982:Hypertonic Solutions; D003973:Diatrizoate; D007483:Iothalamic Acid; D008353:Mannitol; D003974:Diatrizoate Meglumine; D001285:Atropine; D008784:Methysergide